1. Field of the Invention
The present invention relates to a zoom lens with a vibration reduction function and, more particularly, to a vibration reduction technology for zoom lenses having a long back focal length so as to suitable for use with an electronic image equipment employing CCD imaging devices and the like.
2. Related Background Art
The demand for increased performance of zoom lenses in recent years has resulted in a variety of types of zoom lenses. In particular, zoom lenses for an electronic image equipment, such as video cameras and digital still cameras, have employed to date so-called Yamaji-type zoom lenses and four-group type zoom lenses having, in order from object side, positive-negative-positive-positive refractive power arrangement. However, disclosure of a vibration reduction method relating to these types of zoom lenses is rare and, so far, only one publication of Japanese Laid-Open Patent Application No. 7-199124, filed by the present applicant, is known. With the progress in lens barrel technology in recent years, zoom lens types having five or more lens groups have been proposed. However, it has been extremely difficult to simultaneously achieve superior imaging performance, superior vibration reduction function, an increased field of view, increased variable power (i.e. an increased zoom ratio), a compact size, and the like.